Global Positioning System Policy and Program Update

Inaugural Forum Satellite Positioning Research and

Application Center Tokyo, Japan 23 April 2007

James J. Miller, Senior GPS Technologist Space Communications and Navigation Space Operations Mission Directorate

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• GPS Policy – Objectives and Management

• System Improvements & Modernization • Interoperability & International Collaboration • NASA GPS Space Activities • Summary

Overview

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• U.S. Space­Based Positioning, Navigation, and Timing (PNT) Policy – Signed on 8 Dec 04; publicly released on 15 Dec 04 – Updated U.S. policy while retaining prior GPS principles

• Established a stronger National Space­Based PNT Executive Committee; IGEB disestablished – Chaired by Deputy Secretaries of Defense and Transportation

• Created a new National Coordination Office • Created a new Advisory Board from private sector • Enabled new ways to fund future GPS modernization for civil applications

2004 U.S. PNT Policy Overview (GPS!)

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U.S. Policy Principles

• No direct user fees for civil GPS services • Open public signal structure for all civil services

– Promotes equal access for user equipment manufacture, applications development and value­added services

– Facilitates open market driven competition • Use of GPS time, geodesy, and signal standards • Global compatibility and interoperability of future systems with GPS

• Protect the current radionavigation spectrum from disruption and interference

• Recognition of national and international security issues and protecting against misuse

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New Policy: Goals

• Provide uninterrupted availability of PNT services • Meet growing demands in national, homeland, economic

security, scientific, and commercial uses • Continue to provide civil PNT services

– Ensure they exceed, or are at least equivalent to, those of foreign civil space­based PNT services

• U.S. space­based PNT services remain essential components of internationally accepted services

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National Management of GPS

WHITE HOUSE WHITE HOUSE

NATIONAL SPACE­BASED PNT

EXECUTIVE COMMITTEE

Co­Chairs: Defense, Transportation

NATIONAL SPACE­BASED PNT

EXECUTIVE COMMITTEE

Co­Chairs: Defense, Transportation

ADVISORY BOARD

Sponsor: NASA

ADVISORY BOARD

Sponsor: NASA

Defense Defense

Transportation Transportation

State State

Commerce Commerce

Homeland Security Homeland Security

NASA NASA

Joint Chiefs of Staff Joint Chiefs of Staff COORDINATION

OFFICE

Host: Commerce

COORDINATION OFFICE

Host: Commerce

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• GPS Policy • System Improvements & Modernization

– GPS Constellation Status

– Next Steps for Space and Control Segments

• Interoperability & International Collaboration • NASA R&D Activities • Summary

Overview

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The Global Positioning System

• Baseline 24 satellite constellation in medium earth orbit • Global coverage, 24 hours a day, all weather conditions • Satellites broadcast precise time and orbit information on L­band radio

frequencies • Two types of services:

– Standard (free of direct user fees) – Precise (U.S. and Allied military)

• Three segments: – Space – Ground control – User equipment

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GPS is a Global “Public Good”

• GPS services are like a “super lighthouse” – USG Owned & Operated

– Paid for by U.S. taxpayers and provided free to the world – Users are not hailed at port for fee or tax collection – Managed at a national level as a multi­use asset – Acquired and operated by Air Force on behalf of USG

• GPS receivers are like AM/FM radios – Whenever, wherever ­­ without advertising!! – Adding users costs nothing – Tracking its usage is impossible through GPS itself

• GPS is not a fee­for­service utility like cable TV – Usage is not metered ­­ direct cost to user is “zero” – Civil access is open and unconstrained by “locks” or encryption

– Public domain documentation » Available on an equal basis to users and industry

worldwide » Anyone can develop user equipment

“Lighthouses in the sky, serving all mankind”

Dr. Ivan A. Getting (1912–2003)

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GPS Constellation Status as of 12 Feb 07

• 15 Block IIA satellites operational

• 12 Block IIR satellites operational

• 3 Block IIR­M satellites operational – 5 additional IIR­M satellites to launch

– Since Dec 93, U.S. Government met/exceeded civil GPS service performance commitments – SPS Performance Standard (PS)

– U.S. DoD committed to superior GPS service

30 Healthy Satellites Baseline Constellation: 24

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GPS Monitoring Stations

Cape Canaveral

Original USAF Sites ­ 6 NGA sites transmitting to OCS since Aug 2005 ­ 6 NGA sites transmitting to OCS since Dec 2006 ­ 5

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GPS Single Frequency Performance

System accuracy far exceeds current standard System accuracy far exceeds current standard

Steady decrease in error due to improvements such as the addition of new monitoring stations, tighter control of clocks, etc.

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• GPS Policy • System Improvements & Modernization

– GPS Constellation Status

– Next Steps for Space and Control Segments

• Interoperability & International Collaboration • NASA R&D Activities • Summary

Overview

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GPS Modernization Goals

• System­wide improvements in: – Accuracy – Availability – Integrity – Reliability

• Robustness against interference • Improved indoor, mobile, and urban use • Interoperability with other GNSS constellations • Backward compatibility

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Block IIA/IIR Block III Block IIR­M, IIF •Backward compatibility

•4th civil signal (L1C)

• Increased accuracy

• Increased anti­jam power

•Assured availability

• Increased security

•System survivability

•Search and Rescue

IIR­M: IIA/IIR capabilities plus

• 2nd civil signal (L2C)

• M­Code (L1M & L2M)

IIF: IIR­M capability plus

• 3rd civil signal (L5)

• Anti­jam flex power

Basic GPS

•Standard Service

– Single frequency (L1)

–Coarse acquisition (C/A) code navigation

•Precise Service

–Y­Code (L1Y & L2Y)

–Y­Code navigation

Increasing System Capabilities w Increasing Defense / Civil Benefit

GPS Modernization Program

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Modernized GPS – Civil Signals

• Second civil signal (“L2C”) – Designed to meet commercial needs

» Higher accuracy through ionospheric correction » Higher effective power and improved data structure reduce interference, speed up signal acquisition, enable miniaturization of receivers, may enable indoor use

– Began with GPS Block IIR­M in Sep 2005; 24 satellites: ~2014

• Third civil signal (“L5”) – Designed to meet demanding requirements for transportation safety

(safety­of­life) » Uses highly protected Aeronautical Radio Navigation Service (ARNS) band

– Begins with GPS Block IIF – First launch: ~2008; 24 satellites: ~2016

• Fourth civil signal (“L1C”) – Designed with international partners to enable GNSS interoperability – Begins with GPS Block III – First launch: ~2013; 24 satellites: ~2021

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GPS Modernization – Spectrum

ARNS Band RNSS Band ARNS Band

1575.42 1227.6 Frequency (MHz)

1176.45

­250

­240

­230

­220

Pow

er Spectrum (d

BW/Hz)

1575.42 1227.6

­250

­240

­230

­220

Pow

er Spectrum (d

BW/Hz)

Frequency (MHz)

1575.42 1227.6 Frequency (MHz)

1176.45

­250

­240

­230

­220

Pow

er Spectrum (d

BW/Hz)

1575.42 1227.6

­250

­240

­230

­220 Pow

er Spectrum (d

BW/Hz)

Frequency (MHz)

P(Y) C/A

L5

M L2C

L1C

L1 L2

L5

Block IIA, 1990

Block III, 2013

Block IIR­M, 2005

Block IIF, 2008

as of Dec 2005

(artist’s concept)

planned

previous

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IIR­15(M) Launch & View From Space 25 September 2006

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GPS III Acquisition Approach

Block A Configuration • New L1C Signal • New GPS III SV Platform

Block A Configuration

Block A Configuration

Technology Development / Capability Insertion Program Plan

Plus demo high­speed communication (uplink, downlink & crosslink)

Plus new capabilities demo

Plus new capabilities demo

Block A Configuration

Increment IIIA

Increment IIIB

Increment IIIC

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The next generation GPS control segment (OCX) includes a new infrastructure with functionality that completes modernization capabilities.

Monitor Stations Monitor Stations

Advanced Ground Antennas

Advanced Ground Antennas

IIF IIF III III

C2 Uplink

and Downlink

C2 Uplink

and Downlink

Position, Velocity,

Time Data

Position, Velocity,

Time Data

Master Control Station Master Control Station

FAIRBANKS

USNO WASH D.C.

NEW ZEALAND

ECUADOR

ARGENTINA

ENGLAND

BAHRAIN

SOUTH AFRICA

SOUTH KOREA

COLORADO SPRINGS

VANDENBERG, AFB

HAWAII

CAPE CANAVERAL

ASCENSION

DIEGO GARCIA

KWAJALEIN

TAHITI

Master Control Station (MCS) Advanced Ground Antenna

Ground Antenna (GA) USAF Monitor Station (MS)

National Geospatial­Intelligence Agency (NGA) Tracking Station

Alternate Master Control Station (AMCS) AUSTRALIA

IIR/M IIR/M

Battlespace Awareness Battlespace Awareness

OCX Program Description

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• GPS Policy • System Improvements & Modernization

– GPS Constellation Status

– Next Steps for Space and Control Segments

• Interoperability & International Collaboration – GPS­QZSS Progress

• NASA R&D Activities • Summary

Overview

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GPS/QZSS Agreement – 27 January 2006 Unprecedented Compatibility & Interoperability

• QZSS designed to work with & enhance civil services of GPS – Availability enhancement – Performance enhancement

• GPS & QZSS have established that their signals are RF compatible

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GPS­QZSS Technical Working Group (TWG)

• Civil system for Asia­Pacific region • Enhances civil GPS services • First QZSS launch expected in 2009 • GPS­QZSS technical meetings

– Nov 04 in Washington, DC, US – July 05 in Hawaii, US – January 06 in Tokyo, Japan – Aug 06 in Hawaii – Next mtg. in Washington, DC, in May

• GPS & QZSS success in designing “common” signals – Five of six QZSS signals use same

signal structures, frequencies, spreading code families, data message formats as GPS or SBAS signals

• Draft interface specification (IS) for QZSS released in January 2007 – IS­GPS­200, IS­GPS­705, & IS­GPS­800 are baseline documents

% Time that at Least 1 of 3 QZSS Satellites Is Visible

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• GPS Policy • System Improvements & Modernization

– GPS Constellation Status

– Next Steps for Space and Control Segments

• Interoperability & International Collaboration – GPS­QZSS Progress

• NASA R&D Activities – GPS to Earth Orbit, and Beyond

• Summary

Overview

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GPS and Human Space Flight

Miniaturized Airborne GPS Receiver (MAGR­S) • Modified DoD receiver to replace TACAN on­

board the Space Shuttle • Designed to accept inertial aiding and

capable of using PPS • Single­string system (retaining three­string

TACAN) installed on OV­103 Discovery and OV­104 Atlantis, three­string system installed on OV­105 Endeavour (TACAN removed)

• GPS taken to navigation for the first time on STS­115 / OV­104 Atlantis

STS­115 Landing

Space Integrated INS/GPS (SIGI) • Receiver tested on shuttle flights prior to

deployment on International Space Station (ISS)

• The ISS has an array of 4 antennas on the T1 truss assembly for orbit and attitude determination

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Navigation with GPS: Space­Based Range

• Space­based navigation, GPS, and Space Based Range Safety technologies are key components of the next generation launch and test range architecture

• Provides a more cost­effective launch and range safety infrastructure while augmenting range flexibility, safety, and operability

• Memorandum signed in November 2006 for GPS Metric Tracking (GPS MT) by January 1, 2011 for all DoD, NASA, and commercial vehicles launched at the Eastern and Western ranges

GPS­TDRSS Space­Based Range

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Augmentation of GPS in Space: GDGPS & TASS

• TDRS Augmentation Service for Satellites (TASS) provides Global Differential GPS (GDGPS) corrections via TDRSS satellites

• Integrates NASA’s Ground and Space Infrastructures

• Provides user navigational data needed to locate the orbit and position of NASA user satellites

47 o W 171 o W

85 o E

~18­20 o

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Navigation with GPS beyond LEO

•GPS Terrestrial Service Volume –Up to 3000 km altitude –Many current applications

•GPS Space Service Volume (SSV) –3000 km altitude to GEO –Many emerging space users –Geostationary Satellites –High Earth Orbits (Apogee above GEO altitude)

•SSV users share unique GPS signal challenges –Signal availability becomes more limited –GPS first side lobe signals are important –Robust GPS signals in the Space Service Volume needed –NASA GPS Navigator Receiver in development

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Navigation with GPS beyond Earth Orbit … and on to the Moon

• GPS signals effective up to the Earth­Moon 1 st Lagrange Point (L1) • 322,000 km from Earth • Approximately 4/5 the distance to the Moon

• GPS signals can be tracked to the surface of the Moon, but not usable with current GPS receiver technology

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Earth­Moon Communications and Navigation Architecture

• Options for Communications and/or Navigation: – Earth­based tracking, GPS, Lunar­orbiting communication and navigation satellites

with GPS­like signals, Lunar surface beacons and/or Pseudolites • The objective is integrated interplanetary communications, time dissemination, and

navigation

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Summary

• Continuing success in GPS sustainment & modernization – New capabilities delivering enhanced performance – Developments on track to enhance space and control segments

• Civilian use of GPS, and GPS­derived systems, is already extending well beyond Earth

• International participation will make new worldwide GPS applications grow more robust and valuable for generations to come